In many industries, as, for example, in the mattress or bedding industry, it is common practice to secure two wires or rods, such as a spring element of a mattress, to a border wire with clips made from sheet metal. Such clips are generally in a U-shape having an arcuate crown portion and oppositely spaced leg portions depending from the crown portion. The two wires to be connected are placed between the leg portions of the clip and the leg portions pushed together by a clinching tool, thus securing or locking the two wires together.
Such a clinching tool typically includes a J-shaped jaw into which the leading clip of a stack of clips is indexed. The clinching tool has a blade which shears off the first clip from a stack of clips placed inside the clinching tool. U.S. Pat. No. 2,574,811 shows such a clinching tool.
In order to operate the clinching tool, it is necessary to place a plurality of clips inside the clinching tool in an orderly fashion. The clips must be similarly oriented and in an abutting relationship to one another, each clip abutting the two adjacent clips in an orderly fashion.
Clips must be interconnected to each other in a flexible manner so that the stack of clips can be wound into the clinching tool.
The clips must also be interconnected with sufficient strength so that they are able to withstand high tensile forces associated with winding and unwinding of the stack of clips upon a spool in the clinching machine. Accidental breakage of the connector connecting adjacent clips would be detrimental to the operation of the clinching machine.
One common way used to interconnect similar U-shaped sheet metal clips together is by means of non-metal, elongated flexible members made of plastic. Slots or grooves through the arcuate portion of each U-shaped clip are lined up, such that the non-metallic flexible members may be placed inside all of the grooves in order to connect the clips together in a flexible manner.
Several techniques have been developed to secure the non-metallic flexible connectors inside the slots of each clip. U.S. Pat. No. 5,303,821 discloses deforming the side edges of the arcuate crown portion of each clip inwardly so as to crimp the plastic connectors inside the grooves or slots on the arcuate top portions of the sheet metal U-shaped clips. U.S. Pat. Nos. 5,564,564; 5,682,994 and 5,878,880 each disclose a U-shaped clip having tabs extending upwardly from slots formed in the arcuate crown portion of the clip. After connectors are placed inside the slots of a plurality of aligned clips, a roller or rollers pass over the arcuate crown portions of the clips to push down the tabs of each clip, thereby securing the connectors inside the slots.
U.S. Pat. No. 5,878,880 discloses a clip made of sheet metal having a U-shaped hook portion inside which is secured a sheet of cushioning material, such as plastic. When a wire is placed inside the hook portion, the cushioning material prevents wire-on-wire noise, such as squeaking. U.S. Pat. No. 5,833,064 discloses another such clip having a plastic liner to prevent metal-on-metal squeaking or ‘noise”. Over time, these plastic liners may wear out or move/shift.
These two patents, U.S. Pat. Nos. 5,878,880 and 5,833,064, disclose U-shaped clips which may be connected to identical clips in a string and which have prongs or tacks inherently formed from the sheet metal, the prongs being bent downwardly and adapted to be inserted into wooden rails of furniture frames. These prongs or tacks have a smooth surface which may not hold the clip inside wooden rails of furniture frames as securely as desired.
Thus, there is a need for a U-shaped clip assembly which may be made partially of metal and partially of plastic which does not result in squeaking or “noise” over time.
There is further a need for a U-shaped clip assembly which may be constructed of less sheet metal than known clips, thereby reducing the cost of the clips.
There is further a need for a lower shroud for a U-shaped clip assembly which provides improved holding strength when inserted inside wooden rails of furniture frames.